PURPOSE: To reduce current consumption by turning off a switching element in a fixed time after a switch is on to make a second pull-up resistance turn off an a current supply to a contact decrease.

CONSTITUTION: A first pull-up resistance R1 of no-voltage, a second pull-up R2 installed in parallel to the first pull-up resistance R1, a switching element 5 installed in series with the second pull-up resistance R2, a control circuit to turn on and off a switching element 5 and a switch 6 installed in series with a parallel circuit of the first pull-up resistance R1 with the second pull-up resistance R2 are provided. The switching element 5 is turned off in a fixed time after a switch 6 is on to turn off the second pull-up resistance R2 and reduce a current to be supplied to the contact. When the switch 6 is turned on, therefore, a little larger rush current is made to flow so that the oxide film on the contact face can be broken, and immediately thereafter, the rush current can be controlled. Thereby, it is possible to reduce current consumption.